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Fiber Optic Sensor – Monitoring Precast Beams
The Need
A new bridge over the Rio Puerco river, west of Albuquerque will be the first of its kind in the nation with built-in fiber-optic sensors to monitor stress in the bridge's girders. Known as "smart bridge" technology, the self-monitoring system offers many advantages over methods that rely largely on visual inspections. Fiber-optic sensors can monitor shrinkage, creep and other processes that cause weakening in high-performance concrete structures.
The Technology
For bridge safety monitoring, the use of fiber-optic sensors can provide information on the effects of stress long before signs of fatigue begin to show visibly, allowing engineers to address potential problems before they become serious and costly. Sensor enables precise strength measurement as the concrete cures, as pieces are trucked to the site and placed and during the first year of use. Data from such systems can be downloaded on-site, which will be the case for the Rio Puerco bridge, or transmitted to a remote location. The monitoring system installed on the I-10 bridge in Las Cruces transmitted data by cellular telephone to computer of Dr. Rola Idriss, principal investigator for this project, on the NMSU campus.
The Benefits
- The data will be immediately useful, from the time the concrete is poured for the girders, as they are transported to the site, during the construction of the bridge, and while it is in service.
- The built-in monitoring system will provide data for assessing the performance of the concrete, which is expected to withstand heavier loads and last longer than ordinary concrete.
Status
The Rio Puerco bridge, being built for an Interstate 40 frontage road about 15 miles west of Albuquerque, is the first U.S. bridge to have this type of monitoring system built into the girders. The Rio Puerco bridge monitoring project is being funded by the state Highway and Transportation Department, the Federal Highway Administration and the National Science Foundation. Collaborating on the project is the University of New Mexico, which is involved in testing the high-performance concrete. Installation of the fiber-optic instrumentation and the pouring of concrete for the girders took place in July. The bridge construction is expected to be completed by the end of the year.
Barriers
- The price of sensors is expensive.
- Careful installation and protection method during construction should be considered.
Points of Contact
- Dr. Rola Idriss. Bridge Research Program, New Mexico State University, Box 3001, MSC 3-CE, Las Cruces, NM 88003, Tel: (505) 646-3818, Fax: (505) 646-6049. E-mail: ridriss@nmsu.edu
- Dr. Ken White. Bridge Research Program, New Mexico State University, E-mail: krwhite@nmsu.edu
Refrences
- Engineering News Record. Vol. 245 No. 9, Pg. 20, Section: NEWS SITE. Sept. 4. 2000.
- News Releases, New Mexico State University http://www.nmsu.edu/~ucomm/Releases/2006/november/bridge_testing.htm
- Bridge Research Program, New Mexico State University
Disclaimer Statement
Neither the Construction Industry Institute nor Purdue University in any way endorses this technology or represents that the information presented can be relied upon without further investigation.